Monday, 6 August 2012

High Speed Flash Synchronization

High speed synchronization or high speed sync is how modern cameras and flashes attain speeds that are above their normal sync speed. FP flash function is set on the flash control panel.

How Does High Speed Flash Sync Work?

High speed flash sync also referred to as “long burn” flash, works by increasing the time duration of the flash to put out a constant stream of light till the moving slit formed by the focal plane shutter completes its journey across the sensor. We are now familiar with our compact flashes and know that they fire at speeds far greater than 1/1000 of a second. So in high speed sync mode the flash is made to fire many times per second practically producing a continuous beam of light. Although it is a lot of work for the small flashes to do but it is possible because what we are talking about here is actually a very very short period of time. Speeds in excess of 1/200 th of a second (standard sync speed of digital camera employing focal plane shutter). As the light output stays for the entire duration of the exposure, each area receives the same amount of illumination from the flash and hence there are no issues of parts of the frame blacking out. High speed sync permits the use of very high shutter speeds even as high as 1/8000 of a second.

High Speed Flash Synchronization
Photo By Photo Art

One major drawback of the high speed sync feature is that it reduces the power output of the flash unit, the faster the shutter speed used, the lower the power of the flash. For example if a shutter speed of 1/500 second is used for a shot, the guide number of the Speedlite becomes less than half its normal rating, and if the shutter speed is further increased to 1/2000 the flash power drops to less than a quarter.

Uses of High Speed Flash Sync

Stop Motion

The most important feature of high speed sync is that if facilitates the use of higher shutter speeds that Stops Motion. It helps you ‘freeze’ the movement of the subject while the flash acts as a fill light source adding details to the shadow areas.

Depth of Field - Balance Flash Light with Ambient

By saying balance flash power with ambient we are always referring to sunlight. High speed sync flash is mostly used when shooting portraits outdoors in broad daylight as it helps you use wider apertures facilitating creative use of depth of field in your photos.

High Speed Flash Synchronization
Photo By Scottbaldwin

In the next article we will discuss about Photography - Lighting - Flash - Focal Plane Shutter

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